But Anthony Gardner said America had to face up to “soft power” issues too and be a “world leader in every sense”.
He said the US leader was “absolutely right” to talk about “burden-sharing” when it came to contributing to the defence budget.
The former diplomat told CNBC: “Every president really has emphasised the importance of European’s spending more on their defence, he [Mr Trump] was quite right to do that.
“He did it in a much more aggressive way than prior presidents but it’s not a new theme.”
Anthony Gardner praised Donald Trump's speech but called for more "burden-sharing"
Every president really has emphasised the importance of European’s spending more on their defence, he [Mr Trump] was quite right to do that
“But we should be realistic that the spending by European countries is not going to increase overnight, it’s going to take many many years and we all should be spending more time talking about how the money is spent, not just how much money but how it is spent on combat-ready equipment.”
He then suggested America needed to do more to help out with the migrant crisis.
Mr Gardner said: “He’s absolutely right to talk about burden-sharing in the military sector but he’s now flown to Sicily and it’s not being held in Sicily by pure coincidence – it is being held there because Italy is on the front line of a migration crisis.
“And Europeans are saying, particularly Italy, is saying ‘we want burden-sharing in that issue as well’ and the administration is saying ‘we’re not prepared to engage in burden-sharing on migration’ and they’re also saying ‘we’re not prepared to engage in burden-sharing on climate change’.”
NATO countries' heads of states gather in Brussels
Thu, May 25, 2017
NATO countries' heads of states and governments gather in Brussels for a one-day meeting
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U.S. President Donald Trump and Britain's Prime Minister Theresa May react during a ceremony at the new NATO headquarters in Brussels
The comments come after President Trump berated fellow Nato members in a scathing speech.
He said: “I have been very very direct… in saying that Nato members must finally contribute their fair share and meet their financial obligations.
“But 23 of the 28 member nations are still not paying what they should be paying and what they’re supposed to be paying for their defence.”
Mr Trump continued: “This is not fair to the people and taxpayers of the United States and many of these nations owe massive amounts of money from past years and not paying in."
“Over the last eight years, the United States spent more on defence than all other Nato countries combined. If all Nato members had spent just 2 per cent of their GDP on defence last year, we would have had another $199billion for our collective defence.”