On 19 May 2015, as home secretary, Theresa May, was openly criticised at the Police Federation conference by a former Manchester police officer, Inspector Damian O’Reilly, who had been named community officer of the year in 2010, but had subsequently resigned in frustration over policing cuts. He told May bluntly: “We run the risk here of letting communities down, putting officers at risk and ultimately risking national security.” May accused the police of “scaremongering”.

May wants to be elected on a strong and stable platform. But her actions belie her words. Jeremy Corbyn is absolutely right to identify British foreign policy as a proximate cause of – not a justification for – terrorist threats (Report, 26 May). Six weeks ago, the PM led a trade mission to Saudi Arabia. Under fire from Labour, she denied the UK had been selling its principles for the sake of trade deals for the post-Brexit era. Saudi Arabia is primarily important for selling us oil, and spending billions on buying arms. But what is the record of the Saudis in combating extremism? On 5 October 2014, retired General Jonathan Shaw told the Daily Telegraph that Qatar and Saudi Arabia were “primarily responsible for the rise of the extremist Islam that inspires Isil terrorists,” emphasising “This is a timebomb funded by Saudi and Qatari money and that must stop.”

Arms sales and oil are the reason ministers refuse to face up to the perverse reality of Saudi support for terrorism, both against Iran-backed Shia Muslims in Syria and Iraq over the past decade, and innocent concertgoers in Manchester this week, when murderously attacked by an Islamic State-supporting suicide bomber, whose very ideology is exported from, and funded by, the Saudis.

David Lowry

Stoneleigh, Surrey

• The killing of children is always tragic, whether they are in Manchester, Syria or anywhere else. But politicians don’t treat them all equally. While President Trump and Theresa May condemn the cruel murder of “beautiful babies”, they are both busy selling billions of pounds’ worth of weaponry to the government of Saudi Arabia, who use them to bomb thousands of civilians in Yemen, including over 900 children killed. Millions of those who survive are being starved into submission by a Saudi military blockade. The arms sales breach British law, which bans sales where “there is a clear risk that the items might be used in the commission of a serious violation of international humanitarian law” – as the repeated Saudi bombing of schools and hospitals clearly is. Like Islamic State, the Saudi government beheads, crucifies, amputates and flogs its own citizens, often for actions we would count as a normal part of the democratic process. Trump and May claim that Saudi Arabia is helping us in the fight against terrorism, but selling them the weapons to bomb children on a massive scale is surely part of the problem. The Conservative candidate, Victoria Borwick, refused, as my MP, even to meet me or comment on the detailed evidence I provided her with.

John Cummings

London

• Jeremy Corbyn’s attempt to draw a link between Britain’s foreign policy and terror is disingenuous. Islamist terrorism preceded, not followed the west’s “war on terror”. Qutb and Mawdudi produced Islamism long before the Iranian revolution. But, despite all its influence on the young Muslims, Islamism remained a marginal heterodoxy. Qutb and Mawdudi were theological dabblers, whom Sunni scholars had already refuted and dismissed. It was Ayatollah Khomeini who revived the concept and gave modern Islamists religious respectability they had previously lacked. Khomeini promised a constant struggle against the satanic west in 1979. The first instalment of that struggle was delivered in the form of an attack on US marines in Beirut in 1983, killing 241 of them. Under these circumstances, it is difficult to see how Jeremy Corbyn can possibly blame the west for the rise of Islamist terrorism in Europe.

Randhir Singh Bains

Gants Hill, Essex

• The intelligence and security committee, in its 2003 report, International terrorism: war with Iraq, “assessed that al-Qaida and associated groups continued to represent by far the greatest terrorist threat to western interests, and that threat would be heightened by military action against Iraq”. During the Iraq war inquiry (Chilcot), Eliza Manningham-Buller, director general of MI5 from 2002-07, when asked “to what extent did the conflict in Iraq exacerbate the overall threat that our service and your fellow services were having to deal with from international terrorism?” replied: “Substantially.” Indeed, she asked for a doubling of the MI5 budget in the aftermath of the Iraq invasion to counter this increase in terrorism. Though opprobrium will be heaped on him for daring to say it, Jeremy Corbyn is clear-thinking and right in advocating a foreign policy that “reduces rather than increases the threat to our country”.

John Boaler

Calne, Wiltshire

• Gaddafi didn’t just “fall” (Why Libya is still a global terror threat, 26 May): his state was relentlessly bombarded for seven months by international forces until he was dead and his state broken, the fragments handed over to rebel forces on the ground. Salman Abedi’s father, reportedly on the ground with the al-Qaida-linked Libyan Islamic Fighting Group, and the RAF in the air, would have fought on the same side. Sabratha fell into the hands of the armed rebels who became Isis as a direct result of a massive aerial bombardment delivered by our own politicians. Thirty British tourists were slaughtered in Sousse, Tunisia, by someone apparently trained in Sabratha. The RAF was particularly prominent in cracking the besieged city of Sirte open for the militias on the ground – who became Isis and turned the area, as Alia Brahimi says, into its “north African proto-state”.

British politicians (with some honourable exceptions, including Jeremy Corbyn and John McDonnell) voted for the 2011 bombing and enabled the triumph of Salafist jihadism in Libya. Gaddafi always said the west was supporting al-Qaida, and it is hard to believe that they did not know this is what they were doing. The government seemed happy to see jihadists such as (reportedly) Abedi’s father, move freely between Libya and Britain – because they were on the same side. The fruits of that 2011 bombing campaign have been even more bitter for the Libyan people and all the thousands drowned in the Mediterranean; but surely we in the UK can recognise that those fruits include the deaths of innocent British civilians.

Peter McKenna

Liverpool

• If Theresa May thinks that she can combat terrorism by controlling social media (Report, 26 May), she should consult the Chinese and Russian governments, which have the most experience in this field, and whose attempts to contain opposition of all kinds by controlling the internet has had absolutely no success.

Professor Emeritus Simon Clarke

Coventry

• Join the debate – email guardian.letters@theguardian.com

• Read more Guardian letters – click here to visit gu.com/letters