Donald Trump has reconfirmed his nation's commitment to securing peace in Afghanistan, saying the US military will "fight to win" in the country.
The president said he would not be commenting on troop numbers, and that America's enemies "must never know our plans", as he laid out his strategy for battling terrorism in the region.
In an address to the nation from Fort Myer in Virginia, Trump was light on detail but heavy on promises, as he told allies to boost troops and spending on the Afghanistan war in line with the US.
He also had a warning for Pakistan - saying it has "much to lose by continuing to harbour criminals and terrorists".
The US Secretary of State Rex Tillerson told reporters on Tuesday that Pakistan must adopt a different approach to terrorism after "an erosion of trust":
"There's been an erosion in trust because we have witnessed terrorist organisations being given a safe haven inside of Pakistan, to plan and carry out attacks against US servicemen," said Mr Tillerson.
The Secretary of State added that the US will be "conditioning its support" for Pakistan based on how results are delivered:
"Pakistan must adopt a different approach, and we are ready to work with them to help them protect themselves against these terrorist organisations.
"We are going to be conditioning our support for Pakistan and our relationship with them on them delivering results in this area," added Mr Tillerson.
The decision on Afghanistan suggests a change of heart for the president.
In November 2013, Trump said on Twitter: "We have wasted an enormous amount of blood and treasure in Afghanistan. Their government has zero appreciation. Let's get out!"
Here are the key points from Trump's address.
- A commitment to securing victory in Afghanistan
The US currently has around 8,400 troops in Afghanistan. Despite calling for withdrawal from the country before he was elected president, Trump has now reconfirmed his country's commitment to securing victory against the Taliban and Al-Qaeda.
Ahead of his speech, US officials said they expected the president to go along with a Pentagon recommendation to send nearly 4,000 new troops to the country. But Trump has now said: "We will not talk about numbers of troops or our plans for further military activities."
Pulling out of the country could "create a vacuum that terrorists" such as Al-Qaeda and Islamic State could "instantly fill".
But he insisted the U.S. would not offer "a blank check" after 16 years of war, and said he would not be tied to "arbitrary timetables" for withdrawal.
- A warning to Pakistan
The president had a stark warning for Afghanistan's neighbour Pakistan. He accused it of giving sanctuary to "agents of chaos, violence and terror," adding the US can "no longer be silent" about terrorist safe havens there.
Pakistan has "much to gain" from cooperating in the fight against terrorism, he said, but "much to lose by continuing to harbour criminals and terrorists".
- A call to allies to increase troops and spending in line with the US
He called on Nato to increase troops and funding for the war in Afghanistan "in line with our own".
He said: "We will ask our Nato allies and global partners to support our new strategy with additional troop and funding increases in line with out own - we are confident they will."
There are currently about 500 British troops there and around a further 85 had been promised in non-combat roles.