WASHINGTON (REUTERS) - US Secretary of State nominee Mike Pompeo promised on Thursday (April 12) that he would be willing to break from President Donald Trump if necessary, saying he would take a tough line with Russia and that he wanted to "fix" the Iran nuclear deal.

Pompeo, who is currently director of the CIA, blamed tensions between Moscow and Washington on Russia's "bad behavior" and said he would support more American sanctions against Russia.

"(Russian President) Vladimir Putin has not yet received the message sufficiently," Pompeo told the Senate Foreign Relations Committee during his relatively smooth confirmation hearing.

He said Russia's push into Ukraine and other countries needed to be curbed."We need to push back in each place and in every vector," Pompeo said. "We need to make sure that Vladimir Putin doesn't succeed in what he believes his ultimate goal is."

Critics, including some in Trump's own Republican Party, have accused the president of taking too soft a line on Putin. Trump has denied this - and in recent days has been strongly critical of Moscow's backing of Syrian President Bashar al-Assad - but he has also talked of wanting better relations with Putin.

Trump nominated Pompeo to become the country's top diplomat on March 13 after firing Rex Tillerson. Tillerson, a former chief executive of Exxon Mobil, had a rocky relationship with Trump in just over a year in the job.

The start of Pompeo's hearing was disrupted by protesters chanting "No Pompeo, no more war" before police led them out.

And while he faced pointed questions from several Democrats - including about his continued opposition to gay marriage - he was also complimented. Democratic Senator Ben Cardin praised Pompeo's concise answers, and Senator Chris Coons said he was"confident" he would be a strong advocate for diplomats.

Pompeo will need Democratic support to be approved by the committee because one Republican member, Senator Rand Paul, has announced his opposition.

FIX THE DEAL

As a Republican congressman, Pompeo was a strong opponent of the 2015 nuclear pact between Iran and six world powers, which was reached under Democratic President Barack Obama and which lifted many sanctions on Iran in exchange for curbs on Teheran's nuclear programme.

Trump has to decide on May 12 whether to waive Iran sanctions under the deal. He has delivered an ultimatum to Britain, France and Germany saying they must agree to "fix the terrible flaws of the Iran nuclear deal" or he will refuse to extend the US sanctions relief for Iran.

Pompeo said he favoured a "fix" and believed that Iran was not "racing" to develop a nuclear weapon before the deal was finalised, and that he did not expect it would do so if the deal were to fall apart.

"There is no indication that I'm aware of that if the deal were no longer to exist that they would immediately race to a nuclear weapon today," he said.

Similarly, Defence Secretary Jim Mattis said in a separate congressional hearing on Thursday that he also believed the agreement should be fixed and the administration was working with allies to address its flaws.

Among the first issues Pompeo was pressed on was whether Trump spoke to him about the investigation looking into alleged Russian meddling in the 2016 US presidential election.

Pompeo acknowledged he had been interviewed by Special Counsel Robert Mueller, whose federal probe includes looking into whether there was collusion with Moscow by Trump campaign aides. He declined to discuss details.

US intelligence agencies concluded Russia interfered in the campaign in hopes of tilting the election in Trump's favour. Moscow denies this and Trump has denied collusion by his campaign.

'YES MAN' OR NOT

Pompeo appeared emotional at the start of his testimony as he talked about his family and offered personal details, such as his love of meatballs.

Trump developed a warm relationship with Pompeo during White House meetings over the first year of his presidency and believes Pompeo shares more of his world view than Tillerson, who at times disagreed with the president.

Pompeo was questioned repeatedly over whether he would act independently and stand up to Trump. There has been a particularly fast rate of turnover among senior officials in the Trump administration, with the president sometimes souring rapidly against people he appointed.

Pompeo promised he would be his own man as secretary of state, saying his close relationship with Trump meant, "I was able to persuade him" when he headed the CIA.

Senator Robert Menendez, the top committee Democrat, said Trump's "erratic approach" to foreign policy had confused allies and emboldened adversaries.

"Will you stand up to President Trump and advise him differently when he is wrong? Or will you be a yes man?" Menendez asked.

Pompeo promised to rebuild the State Department, which has been gutted by the departure of senior diplomats and found itself sidelined by the White House in foreign policy decisions.

A reorganisation and hiring freeze initiated by Tillerson left the rank and file demoralized, with vacancies in most of jobs that are filled by political appointees.

Pompeo said he would work quickly in his new role to fill the gaps and promised to spend money allocated by Congress for State programmes. Tillerson's failure to do angered both Republicans and Democrats in Congress.

The date for the vote confirming Pompeo in the full Senate has not been set but is likely in the coming weeks.