The Falkland Islands are expected to be discussed at a G20 summit (Picture: Crown Copyright).
Prime Minister Theresa May says "the sovereignty of the Falklands has not changed", as she became the first Conservative Prime Minister to visit Argentina since the 1982 war.
Asked during her flight to Buenos Aires whether the UK remained ready to defend the Islands with military force if necessary, Mrs May said: "I am clear that our position on the sovereignty of the Falklands has not changed.
"What has changed in recent months is we have seen better relations with Argentina."
Mrs May will hold one-on-one talks with Argentine President Mauricio Macri, who is hosting global leaders at the G20 summit.
The Falklands are expected to feature in their discussions but are not expected to dominate talks which focus on trade.
Earlier this week, the two countries agreed an air link between the Falklands and the South American mainland via Argentina.
"I think the announcement we saw earlier this week of the extra flight from the Falklands through to South America is important," Mrs May explained.
"It is important for the Falklands and it is important in showing a different relationship developing.
"I am talking to President Macri about issues about trade and opportunities for trade, but our position on the sovereignty of the Falklands hasn't changed and will not change."
During the G20 summit, Mrs May is not expected to have talks with Russian President Vladimir Putin.
However, Mrs May called on Russia to release the Ukrainian sailors detained after the seizure of three naval ships in the Black Sea last weekend.
"They should release the ships and sailors and de-escalate the situation.
"If you look at what we have seen over the last year of so, this is part of a pattern of Russian behaviour.
"We have always been at the forefront in Europe of asking for sanctions on Russia in relation to its behaviour. We will continue to push for what we consider to be appropriate sanctions on Russia."
This comes after the Ukraine President urged NATO to deploy naval ships to the Sea of Azo.
Meanwhile, the Prime Minister confirmed she will be speaking to Saudi Arabia's Crown Prince Mohammend Bin Salman, following the murder of journalist Jamal Khashoggi and the war in Yemen.
"In relation to Mr Khashoggi, we want to see a full and transparent investigation of what happened and those responsible being held to account," she explained.
"With the issue of Yemen, we continue to be deeply concerned about the humanitarian situation.
"The long-term solution for Yemen is a political solution, and we will be encouraging the parties to work for that political solution."
The PM is expected to use the G20 gathering to push her "global Britain" message, telling other global leaders that her Brexit deal will be good for the world economy.