The worsening situation at makeshift camps in Idlib province comes as Russian-led airstrikes saw at least 18 people killed on Tuesday.
"If Trump arrives along this road, he will be a good man," Assad said, to which Putin laughed before replying, "He will change for the better."
The president has criticized past administrations for not keeping control of valuable Iraqi oil fields conquered by the military.
The Syrian military has accused Israel of bombing the T-4 Base in Homs hours after rockets hit an Iraqi military base used by U.S. and allied personnel near Baghdad.
Syria's prime minister said that "the presence of Americans in Syria is a sign of occupation, and we believe that all nations and governments must stand up to their unlawful presence in the region."
"It's also why they burn tires all the time," said Steve Gumaer, the CEO of Christian nonprofit Partners Relief & Development.
On Friday, Russia used its veto threat to force the United Nations Security Council to adopt a resolution that reduces the delivery of humanitarian aid and access to medical assistance.
As President Donald Trump called on other nations to play an increased role in the Middle East after Iranian attacks on Iraqi bases housing U.S. personnel, Russia and Turkey discussed Libya and Syria.
Less than a week after the U.S. assassinated Iranian Major General Qassem Soleimani, Russian President Vladimir Putin made a rare visit to his Middle Eastern ally, Syrian President Bashar al-Assad.
"We need to be very careful as we move forward," Representative Mark Green cautioned.
Iraq called the U.S. strikes "a violation of the sovereignty of Iraq and a grave violation of the rules of action of the coalition forces, including American forces."
"Russia, Syria, and Iran are killing, or on their way to killing, thousands of innocent civilians in Idlib Province. Don't do it!" the president wrote on Twitter.
"I can compare 2019 with 2012, when they were beginning, organizing themselves," Major General Sirwan Barzani, a Kurdish Peshmerga commander, told the BBC.
As Russia and Syria wrapped up "complex and tense" drills in the Mediterranean, they conducted a flurry of aerial and surface rocket strikes against Islamist-dominated Idlib, also home to millions of civilians.
Turkish President Recep Tayyip Erdogan argued that the goal of his cross-border attack was to clear the way for the resettling some of the 3.7 million Syrian refugees his country hosts.
The Caesar Syria Civilian Protection Act, recently passed by the Senate, sanctions both Russia and Iran for alleged war crimes by Syrian President Bashar al-Assad, whom they continue to back.
As Washington lawmakers hailed the passage of the Caesar Syria Civilian Protection Act, Syrian President Bashar al-Assad appeared ready to push on with a new assault on Islamist-dominated Idlib.
If the U.S. refuses to withdraw from Syria, President Bashar al-Assad warned, "there will be a popular resistance and they will pay the price."
President Donald Trump has retained a small U.S. force in the east of Syria to guard oil fields there against remaining Islamic State elements.
The president previously described a construction project in Istanbul as "a little conflict of interest" in his dealings with Turkey.
Chris Van Hollen said Turkish President Recep Tayyip Erdogan is being allowed to cozy up to Putin "with impunity."
The British rock star, a prominent anti-war activist, was murdered on December 8, 1980.
Turkey's invasion of northeastern Syria has prompted protests from other NATO nations and opened up cracks in the alliance.
Two people were killed last week when an Islamic extremist launched a knife attack in central London.
Turkey began radar testing of its Russian-made S-400 anti-aircraft system on Monday, the purchase of which has created friction with Washington.
Iran and Israel have escalated their conflict in Syria, but they're both looking to Russia to prevent an all-out war.
"Novaya Gazeta" published footage of a man being beaten and killed by men thought to belong to the Wagner military company.