French President Francois Hollande and US President Barack Obama pledged their solidarity in the fight against the Islamic State in Iraq and Syria (ISIS), declaring that they would step up strikes in Syria and Iraq, but neither committed to boots on the ground.
Experts said the show of solidarity and increased pressure would help in the battle against ISIS, but added that the United States could do more in terms of military action.
In an hour-long joint press conference on Tuesday in Washington, Mr Obama said: "The US and France stand united in total solidarity, to deliver justice to these terrorists... and defend our nations."
Mr Obama said the US would continue to share intelligence with France and called on European Union countries to require airlines to share passenger information for better security.
Mr Hollande said that the two sides would "scale up" strikes in Syria and Iraq and "strengthen intelligence-sharing regarding the targets".
IN THE RIGHT DIRECTION
There was no big announcement but the solidarity invoked is most important. There is a diplomatic process going on, and that surely is going in the right direction of a coalition of some kind - a real coalition, not just words.
MR PHILIPPE LE CORRE, visiting fellow at the Centre on the United States and Europe at Brookings Institution
When taking questions, however, Mr Hollande said France "would not act militarily on the ground".
The French leader has been seeking international support for his newly declared war on ISIS after the Paris attacks on Nov 13 that killed 130 people.
The meeting took place amid rising tensions between Russia and Turkey, after Turkey downed a Russian warplane on Tuesday. Both countries are key to resolving the Syrian conflict.
On Monday, Mr Hollande met British Prime Minister David Cameron - who has pledged to press the British Parliament to approve military action in Syria - and on Thursday will meet Russian President Vladimir Putin in Moscow.
Mr Hollande has called on Washington and Moscow to form a grand coalition against ISIS, in the light of the Paris attacks and the downing of a Russian airliner over Sinai last month that killed over 200.
But so far, the US has made it quite clear that working with Russia would be difficult if the two nations continue to bat for different teams. Russia supports Syrian President Bashar Al-Assad, while the US believes that he must be removed.
Mr Obama said: "Russia's strikes against the moderate opposition only bolster the Assad regime... We agree that Russia could play a more constructive role if it shifts the focus of its strikes to defeating ISIL." ISIL is another acronym for ISIS.
The United Nations Security Council passed a France-sponsored resolution last Friday, calling on the international community to "redouble and coordinate" programmes to suppress terrorist acts by "all necessary measures".
"We have a resolution from the Security Council, we must take action against Daesh," said Mr Hollande, using another name for ISIS.
Mr Hollande said that he would indicate to Mr Putin during his visit that strikes in Syria "must be against Daesh, against terrorism and those who precisely are threatening us".
By the end of the week, Mr Hollande will have also met world leaders from Germany, Italy and China in his bid to rally global cooperation, but further commitment from the US and Russia would be a major coup for France.
Said Mr Philippe Le Corre, a visiting fellow at the Centre on the United States and Europe at Brookings Institution: "On the diplomatic and military front, we expected that the US would do a little more. There is only one aircraft carrier at the site, which belongs to France. Out of 10, the US could have put one there to help."
However, Mr Le Corre did not discount the importance of the solidarity shown by the US and other countries around the world.
"There was no big announcement but the solidarity invoked is most important," he said of Tues-day's meeting. "There is a diplomatic process going on, and that surely is going in the right direction of a coalition of some kind - a real coalition, not just words."