Trump spoke during an address Wednesday from the White House after Iran struck back at the United States for killing its most powerful military commander.
Trump has frequently criticized NATO as obsolete and has encouraged participants to beef up their military spending.
He cited more reliance on NATO while also seeking to emphasize U.S. military strength. He said American military and economic strength is the best deterrence to war.
Trump also used his address to speak directly to Iran, saying "we want you to have a future and a great future."
He said the United States is ready to embrace peace and all who seek it.
President Donald Trump says the U.S. will immediately impose new sanctions on Iran in response to its missile attacks on military bases in Iraq that house American troops.
In an address to the nation Wednesday, Trump said those new "powerful sanctions" will remain until Iran abandons its nuclear ambitions and ends its support for terrorism.
Trump also said he would ask NATO to become more involved in the Middle East. That seems to indicate continued U.S. involvement in the region despite Trump's desire to withdraw troops from what he calls "endless wars."
At the same time, Trump says the United State is "ready to embrace peace with all who seek it."
President Donald Trump says the American people should be "extremely grateful and happy" that no Americans were harmed when Iran launched ballistic missiles at two Iraqi bases housing U.S. troops early Wednesday.
Trump says Iran "appears to be standing down" and is crediting an early warning system "that worked very well" for the fact that no Americans or Iraqis were killed.
The launch was Tehran's most brazen direct assault on America since the 1979 seizing of the U.S. Embassy in Tehran and came days after Trump authorized the targeted killing of Gen. Qassem Soleimani, the head of Iran's elite Quds Force.
Iran had pledged to retaliate, bringing the two countries closer to the brink of war.
Trump added: "We have the most powerful and well equipped military anywhere in the world, by far!"
Oxfam says it is restricting its humanitarian work in Iraq due to serious security concerns following Iranian missile attacks on military bases hosting U.S. troops there.
Oxfam's Iraq country director said in a statement Wednesday that humanitarian work, including cash aid, had been suspended in some areas of the country owing to travel difficulties and checkpoints on in remote areas. It added that some Oxfam staff had been relocated to other areas over fears of more violence.
Andres Gonzalez Rodriguez added that if the organization was forced to continue the suspension of aid for a few weeks, "100,000 of the most vulnerable people will be affected."
Oxfam runs 26 programs in five Iraqi governorates providing water and sanitation, food, cash and protection assistance, the statement said.
The Pentagon is confirming that Iran has launched "more than a dozen ballistic missiles" at two targets hosting against U.S. military and coalition forces in Iraq.
Defense Department spokesman Jonathan Hoffman says "It is clear that these missiles were launched from Iran."
He says the attacks "targeted at least two Iraqi military bases" at Ain Assad and Irbil.
Hoffman says the U.S. is "working on initial battle damage assessments."
Iranian state TV says the attack was in revenge for the killing of Revolutionary Guard Gen. Qassem Soleimani, whose funeral Tuesday prompted angry calls to avenge his death.